| Abstrakt: |
The intraduplex reaction of the alkylating reagent CIRCH2NHpd(TTCCCA) (X, CIR is p‐(N‐2‐chloroethyl‐N‐methylaminophenyl) residue) with the target 26‐mer d(TTGCCTTGAATGGGAAGAGGGTCATT) (P) in the presence of effectors was studied. The effectors used were Phn‐L‐pd(TTCAAGGC)p‐L‐Phn (E1) and Phn‐L‐pd(TGACCCTC)p‐L‐Phn (E2), where Phn is N‐(2‐hydroxyethyl)‐phenazinium residue and L is NHCH2CH2NH spacer. The dependence of the alkylation extent of the target on the reagent concentration was treated using the equation derived earlier for the two‐component system (reagent+target) to calculate association constants of X with P, PE1, PE2and PE1E2. The latters were found to be Kxe1= 6.75 · 105M−1, Kxe2= 4.15 · 104M−andKxe12= 5.87 · 106106M−1as compared with the affinity of X to P Kx= 2.16 · 104M−1in the absence of effectors. Taking into account the internal structure of the target, co‐operativity parameters describing interactions in the tandem E1· X · E2arranged at the target were calculated as α1= 16, α2= 10 and α12= 139 for the duplexes PXE1, PXE2and PXE1E2. |
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